Concrete-filled steel tubular column is a very reasonable composite member, which is widely used in the field of civil engineering and construction. On one hand, production of the concrete-filled steel tubular column requires no template, which improves the efficiency of construction; on the other hand, the seismic performance of the concrete-filled steel tubular column is superior to the conventional steel reinforced concrete column. A large number of earthquake damage investigations and experimental studies found that, earthquake damage to the concrete-filled steel tubular column is mainly concentrated at upper and lower ends of the column, while the rest of the column shaft is essentially intact, that is, material performance of the column shaft is not displayed in full strength. Therefore, in the case of amount of steel remains the same, the concrete-filled steel tubular column may be further optimized by adjusting material layout (i.e. increasing the proportion of steel consumed to the upper and lower ends of the column, while decreasing the proportion of steel consumed to the most of rest column shaft), and thereby its seismic performance is improved, but such technology is rarely seen by now.
Since natural sand and gravel mining destroys the environment and the reserves are dwindling, waste concrete, as a valuable “special resource”, its recycle use has attracted more and more attention at home and abroad. However, the waste concrete is obtained by demolishing the constructions built in earlier years, and strength grade is generally low. In the past the waste concrete was only used with fresh concrete with close strength grade, with range of application being subjected to great restraints (for example, cannot be directly applied to high-level, heavy load and other structures), so how to effectively expand the range of application of normal-strength demolish concrete is an urgent problem to be solved. The present invention has found that using a mixture of normal-strength demolished concrete lumps and high-strength fresh concrete can yet be regarded as an effective way to solve this problem.
To sum up, problems exist in the prior art, such as material layout of the seismic concrete-filled steel tubular column being not reasonable enough and the range of application of the normal-strength demolished concrete being urgent to expand.